[c-nsp] IPv6 and ISIS on GSR

[Leif Sawyer]

Pete Templin writes:
> We're beginning our IPv6 deployment, and running into some 
> surprises already.  I've taken a GSR out of the forwarding 
> path and successfully applied some IPv6 addresses to its 
> interfaces.  However, as soon as I put "ipv6 router isis" on 
> any interface, my v4 isis adjacencies drop within the dead 
> interval and the router "falls off the network". 
> Removing the command(s) brings the router back into happy adjacencies.
> 
> My first hunch was that it was a condition of the single 
> topology, so I then tried applying the 'ipv6 router isis' to 
> all interfaces that had 'ip router isis' on them...still no success.
> 
> Any thoughts on what I'm doing wrong?  12.0(32)S8 on a 12008.
> 


If you're mixing IPv6 and IPv6, there's a little more work to do:

Here's kind of a "blanket" config that should cover 95%+

!------------------------------
! You can safely ignore errors here
!
ipv6 unicast-routing
ipv6 cef
ipv6 cef distributed
!
!
!
router isis
  is-type level-2-only
  !
  !  This is the big one, for converged 4+6
  metric-style wide
  no adjacency-check
  !
  address-family ipv6
    multi-topology
    no adjacency-check
!
!
interface Lo0
  description *** Management IP Address
  ipv6 enable
  ipv6 addr 0100:0100:FFFF:FFFF:0000:0000:0000:0017/128
  ipv6 router isis
!
!


You may -still- get route convergence distruptions.  We got around
it by having a separate EIGRP process running at the same time that we
were migrating off of.